If your code is disappearing after saving it in Editor > Settings > Tracking Codes (or in a Custom HTML element or Custom JS element in the Editor), please make sure of the following:
1.) Make sure your tags and code are complete and valid. Even a missing < or ; could break your code.
2.) Make sure to paste your code using keyboard commands, and not your mouse (in other words, don't use the right-click of the mouse to paste the code). This is Command + V on the Mac, and Control + V on the PC.
If you still have trouble, please feel free to reach out to our support team.